1 List of United States cities by population. ^ 2  Population projection is that of the entity known since 2016 as Ciudad de MÃ©xico and previously as the Distrito Federal. ^  Population estimate is that of the Toronto census division, which consists solely of the City of Toronto.
Lens (optics) For other uses, see Lens. A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis.
Eyepieces (ocular lenses): Two removable. lenses that you look through to observe the. specimen or object on the slide. The magnifying power of the ocular. lenses on your microscope is 10X. The circle you can see through the eyepiece. is called the field of view . Note: one of the oculars may have a pointer. used to identify a specific area on the slide.